Optimization of heat transfer in mist/steam cooled square channel with kink angled rib turbulator

In this study, the effects of the orientation and kink angle of a rib turbulator on the flow characteristics and heat transfer performance of two-phase mist/steam flow in a square channel are investigated through numerically. The simulations are performed for a continuous steam phase with a Reynolds number of 147,000 and mist particles of size 10 mu m through the discrete phase. The distribution of the secondary flow and the trajectories of mist particles are investigated to determine the reason for heat transfer enhancement. The simulation results show that the v-shaped rib turbulator with corresponding kink angles strongly influences secondary flow in the channel. This secondary flow forces the mist particles to different positions and collects them near the sidewalls, as well as at the center of the channel. When adopting a v-shaped rib turbulator with a kink angle of 120 degrees, a mist/ steam mass ratio of 1%, and mist particle size of 10 mu m, the average Nusselt number and thermal performance factor in the cooling channel are 75.21 and 38.31%, respectively. Consequently, comparative evaluations show that the v-shaped rib turbulator with corresponding kink angles has higher heat transfer performance than a wedge-shaped rib turbulator in the cooling channels.